Lubricant



Patented Jan. 7, 1941 azzsgzla PATENT LUBRICANT Waldo L. Steiner, Ponca City, th., assignor to 1. Continental Oil Company, Ponca City, Okla a corporation of Delaware No Drawing. Original application February 3, I 1936, Serial N0. 62,170. Divided and this Illplication December 29, 1939, Serial No. 311,600

9 Claims, (01.252-55) My invention relates to a cutting lubricant in particular, and lubricants generally, and more particularly to a lubricant designed for lubrication or .cuttlng tools and machines for cutting and threading metallic pipes, rods, bolts and the like.

This application is a divisional of my co-pending application now Patent No. 2,188,255, bearing date January 23, 1940.

i 1 Heretofore, cutting lubricants consisted main-- 1y of blends of lubricating oil and a chemical combination of sulphur, usually, with a fatty compound. These early types of cutting oils are fairly satisfactory for most uses but nevertheless have certain distinct disadvantages. Most of them have an objectionable odor and are very dark in color and some are very inefflclent. Usually they are rather expensive and diilicult to prepare. A great number have an irritating eilect on the skin of the operator. Some are extremely viscous when cold and are therefore very unsatisfactory on cold mornings in many shops which are not well heated. Some of the newer cutting lubricants contain sulphur 9,5 compounds other than those derived from fatty acid derivatives. In all of the above compounds, however, the sulphur is in chemical combination. Furthermore, other things being equal, the efliciency of this type of outing oil is largegg ly dependent on the instability of the sulphur compound. The more stable the compound the less eillcient it is as an aid in cutting and relatively more of it will have to be used for a satisiactory outing lubricant. On the other hand,

5 it the compound is very unstable. the cutting oil made from it will-likely deteriorate in storage.

The object of my invention is to provide an improved cutting lubricant. I have discovered that an improved and superior cutting lubricant 0 may be prepared by blending a petroleum lubricant with a true physical solution or sulphur in certain suitable solvents. My investigation. of this new type oi cutting lubricant gives sufflcient evidence to prove that it is superior to the conventional chemically combined sulphur cutting lubricant in several ways. In the first place, much less' sulphur is required to obtain the same eiliclency for the lubricant. Secondly, it makes it possible to prepare a cutting lubricant so very light in color and quite odorless and one which does not irritate theskin in the slightest 'degree. Also, they do not congealat low temperatures. While some old type lubricants containing chemically combined sulphur may be ll obtained odorless, they are invariably dark in color and are usually rather viscous around F.

There are many solventsof sulphur, one of the best being carbon disulphide. This solvent could not be used commercially in a cutting lubricant because of its high volatility and in- 5 flammability. There are other solvents for sulphur to which these objections would not apply which, for other reasons, such as obnoxious odor and insolubility in petroleum oil, I do not prefer. Phenol and aniline are examples. .The greatest difliculty in finding a suitable solvent for sulphur for a cutting oil is to discover one which will not allow sulphur to separate outwhen the mixture is stored at relatively low temperatures. Naturally, a marketable cutting lubricant must be stable under all kinds 01 pos-' sible storage conditions such as might be encoun. tered in winter.

I have found that solutions of sulphur in certain derivatives of naphthalene and similar high boiling aromatic compounds when added to a petroleum lubricant, do not precipitate out sulphur even at very low temperatures when the amount of sulphuris kept within certain limits, and'these form the preferred solutions for. use inmyinvention. Naphthalene itself is odoriferous and not very soluble in petroleum oils at low temperatures and, therefore, is not preferred. It is, however, a very efficient solvent for sulphur, especially at high temperatures. Considerable investigation was therefore given to the naphthalene derivatives which are soluble in petro-" leum at low temperatures. This work led to the discovery that, among the better sulphur solvents which are soluble in petroleumat lowhtemperatures are thejchlorlnated derivatives of naphthalene. Furthermore, the best suited ol the chlorine derivatives are the -'pentaand hexachloronaphthalenes. These two compounds were found to be able to dissolve more sulphur tor a given weight when mixed with a petroleum lubricant than any other solvent investigated,

either at high or low temperatures.

' stored for several weeks at 0 F. ii the sulphur content does not exceed 12 percent byweight oi the chloronaphthalene in the mixture. These chloronaphthalenes are themselves soluble in a pe troleum lubricant to the extent of about -10 percent'at 0 1'', They are more soluble in the heavier lubricants such as oils havlng'an S. S. U. 58

viscosity of about 250 at 100 F. than in lighter oils having a viscosity of '70 to 100 at 100 F. Thus it is possible to make a cutting lubricant stable to the most adverse storage conditions from these two chloronaphthalenes, containing 1.2 percent of physically dissolved sulphur. Since sulphur in a physically dissolved state is many times more emclent in a cutting lubricant than when it is in the combined state, this is sufficient to give an excellent and superior cutting lubricant.

Other solvents among the naphthalene derivatives which are satisfactory, but not as emcient as the above two, are as follows in the decending order of their suitability for use in this invention: heptaand higher chlorine derivatives of naphthalene; mono-, di-, tri-, and tetra-chloro derivatives; decahydronaphthalene idecalin); alkylated naphthalenes (methyl and ethyl); coal tar oilcut boiling between 400 F. and 600 F. and higher (largely a mixture of alkyl derivatives of naphthalene) tetralin and other hydrogenated naphthalenes.

Dialkylbenzenes and similar high boiling alkylated benzenes (one or more alkyl groups) are suitable for this invention but are not as efficient as the naphthalene derivatives.

In preparing a cutting lubricant according to my invention, the following procedure is recommended. The petroleum lubricant is first mixed with the sulphur solvent in the proportion that it is calculated necessary for the amount of sulphur to be held in solution. The mixture is heated to slightly above the melting point of sulphur (or about 250 F.) and the sulphur is then stirred in until all dissolves. No chemical Example No. 1.-A mixture of parts by weight of light lubricating oil and 20 parts by weight of mono-chloronaphthalene was heated to 250 F. and one' part of sulphur was stirred in until it dissolved. A sample of this mixture stored at 0 F. for several days did not precipitate sulphur. Tested in a 2" thread cutting machine it save excellent results. The threads were extremely smooth. Its color was very light and its transparency was an aid to the operator in obtaining the best results, thus avoiding a drawback of the dark sulphuretted cutting all containing chemically combined sulphur. On very cold mornings no trouble was encountered from dimculty to flow. A comparison was made between the results obtained with this lubricant and a highly recommended cutting oil containing chemically combined sulphur which lubricant had a larger amount of sulphur than the lubricant of my invention. The test pipe threaded was a piece 01' very hard, used-oil-well casing. A number of threads cut with the sulphur-combined lubricant were compared with a .number of threads cut with the new type lubricant. The latter threads were appreciably smoother and showed less tearing than the former, thus demonstrating the improved efllciency of a physical solution of sulphur as a cutting lubricant.

Example No. 2.-A mixture of 80 parts by weight of a light petroleum lubricant and 20 parts'by weight of coal tar oil (B. P. range 400 F. to 580 F.) was heated to 250 F. and one part by weight of sulphur stirred in until it entirely dissolved. This cutting lubricant was used ma 2'' thread cutting machine for two months with consistently superior results with respect tothe threads obtained while using it.

Eaample No. 3.A mixture of parts by weight of petroleum lubricant and 15 parts by weight of decalin was heated to 250 F. and one part by weight of sulphur was dissolved in it. This cutting lubricant when tested in a thread cutting machine gave very satisfactory results.

Example No. eL-A mixture of 10 parts by .weight of penta-chloronaphthalene and parts by Weight of a petroleum oil with a viscosity of- 150 seconds at F. was heated to 250 F. and l pant by weight of sulphur stirred in until dissolved. On testing this mixture for stability at 0 F. for several days, it did not precipitate out sulphur. It was very light and transparent, having a 2 color (A. S. T. M.) and was entirely free of any odor. The cold test was not raised by the addition of the sulphur and chloro-naphthalene. When tested on a thread cutting machine it gave results which were superior to any obtained from any cutting lubricant ever tested on this machine.

Considerably less sulphur in the blend than was used in the above examples is sufiicient to give a good cutting lubricant. Even as little as .2

percent. sulphur in the blends of my invention gives satisfactory results. Generally, the sulphur content of this type of cutting lubricant should lie between .1 percent and 2 percent. More. will not be necessary and less willnot be entirely satisfactory. The quantity of sulphur to be used is determined by the use to which the cutting oil will be put.

The addition of 51 percent or 2 percent of oleic acid to this type of cutting lubricant seems to have a slightly beneficial effect but is not necessary.

This new type of cutting lubricant may be blended with the old sulphur chemical compound type cutting lubricant to improve the latter.

The petroleum lubricants used in the preparation of these cutting oils may be of naphthenic,

parafllnic or mixed base source. They may be either raw or refined and should be selected so that the finished lubricant will have a viscosity of 100 to 300 seconds at 100 F. (S. S. U.). Naturally, cutting lubricants with viscosities outside this range may be useful but as a rule are not as satisfactory as those within this range.

Although a cutting lubricant is the primary obloci; of this invention, it is possible to obtain a high class extreme pressure gear lubricant by merely substituting a more viscous hydrocarbon lubricant for the relatively low viscosity oil used in preparing cutting lubricants in the foregoing compositions.

Having thus described my invention, I claim: 1. A composition of matter comprising in combination a major proportion of a lubricant and a minor proportion of a. physical solution of elemental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising an alkylated organic compound which is a sulphur solvent and is itself soluble in said lubricant. 1 2. A composition of matter comprising in combination a major proportion of a lubricant and 75 mental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising an alkylated naphthalene which is a sulphur solvent and is itself soluble insaid lubricant.

4. A composition of matter comprising in combination a major proportion of a lubricant and a minor proportion of a physical solution of elemental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising an alkylated derivative of naphthalene which is a sulphur solvent and is itself soluble in said lubricant.

5. A composition of matter comprising in combination a major proportion of a lubricant and a minor proportion of a physical solution of elemental sulphur in uncombined form dissolved in aminor proportion of a solvent comprising an alkylated organic compound which is a sulphur solvent and is itself soluble in said lubricant, said composition of matter containing between one and two percent by weight of oleic acid. j v

6. A composition of matter comprising in combination a major proportion of a lubricant and a minor proportion of a physical solution of elemental sulphur in uncombined form dissolved in a minor proportion of a solvent comprising an alkylated aromatic compound which is a sulphur solvent and is itself soluble in said lubricant, said composition containing between one and two percent by weight ofv oleic acid.

7. A composition of matter as in claim 4 containing in combination between one and two percent by weight of oleic acid.

8. A composition of matter as in claim 4 in which said alk-ylated derivative of naphthalene comprises a coal tar cut boiling between 400 F. and 600 F.

9. A composition of matter as in claim 4 in which said alkylated derivative of naphthalene comprises a. coal tar cut boiling between 400 F. and 600 F., said composition containing between one and two percent by weight of oleic acid.

WALDO L. s'rnnmn. 

